function [sel] = find_protocol(sf, protocol)
% find all incidences of the protocol for the file name selected by
% sf in the current CONTROL database.
%
global CONTROL
sel = [];
fn=CONTROL(sf).filename;
afn = strmatch(fn, {CONTROL.filename}, 'exact');
sels = strmatch(protocol, {CONTROL(afn).protocol}, 'exact');
sel = afn(sels);
return;
